The subject invention discloses an agent for promoting cell adhesion to a support, comprising a dispirotripiperazine derivative represented by Formula I below or a salt thereof; a method for promoting cell adhesion to a support comprising adding the dispirotripiperazine derivative represented by Formula I below or a salt thereof to a culture medium, or applying the same to a support; and an agonist of a heparin sulfate that comprises the dispirotripiperazine derivative represented by Formula I below or a salt thereof, and that promotes cell adhesion and/or cell growth.